The Photonics for Nanoapplications team (PNT) assumes the key role of transferring research and technology know-how to the industry and provides services to the industrial and other organizations through its established "Photonics for Nanoapplications Services Laboratory". Furthermore, the group members experienced in various diverse and complementary fields often participate as industry consultants in issues related to Optics and Optical System Design, Holography; Nonlinear Optics; Photorefractive effects; Guided wave optics; Optical information storage and processing; Laser based materials micro- and nano-processing; Infrared Imaging; Sensors;Radiometry; Infrared systems ; Biomedical applications and instrumentation.

During the past three years the PNT group is building up the info structure in equipment (AFM, Metallographic, Profilometer) and personnel skills to provide services for high-resolution non-destructive Microscopy for industrial and scientific applications.

Fungus constitutes the most important menace to paper. Mycelial structures, whether alive or dead in paper, degraded cellulose by certain tinctorial reactions. Fungicides capable of killing the organisms without damaging the paper itself are not available. It is now believed that the use of aqueous based methods for preserving old paper is insufficient in many cases. Therefore the search for non-contact dry cleaning techniques is highly encouraged. The use of laser-based techniques to remove foxing stains from old paper might be the solution to the problem. But the use of lasers at longer wavelengths is usually accompanied by side effects since the affected areas requires higher laser energies to be cleaned. A yellowish stain mark could be formed in the exposed areas of the substrate as the result of cellulose oxidization by light. On the other hand surface treatment of historic paper by laser light at 157nm, can be a solution to this problem. At deep-UV wavelengths, laser light efficiently destroys spores and fungi, and initial experiments have demonstrated that fungi were completely removed and destroyed following illumination of paper with laser light at 157nm. In order to optimize the methods of laser cleaning of historic paper, foxing ablation experiments at 157 nm indicate that infected paper areas can be removed with controllable spatial resolution in the nanometer scale. In addition foxing samples were investigated by scanning electron microscopy and X-ray analysis. It was found that biological activity was present on paper areas containing traces of iron.

SEM image of paper areas infected by foxing where biological activity can be seen (Jozef Stefan Institute, Deparment for Nanostructured Materials, Abstract)

It is now widely accepted that initial stage of nucleation (crystallization-agglomeration) drives chemical reactions to specific directions, with sound environmental, technological and economical impact.

A technical problem unsolved up to now, is related to the formation of calcium carbonate in the form of calcite on the surfaces of water flow systems (pipes, tanks etc), and it is commonly known as "SCALING". Scale deposits increase operating and maintenance costs by lowering the flow capacities and increasing the energy consumption of pumps in cool water systems, and by lowering the heat transfer in hot water systems with heat exchangers and evaporators. Chemical treatment of water is widely used as a de-scaling method by using polyphosphates. This method has a long-term accumulative effect and it is detrimental for human health and for sensitive ecosystems. As an alternative to the chemical method, the physical treatment of water, e.g. magnetic, is becoming important in preventing a lime scale formation in industrial power plans and other commercial water systems (e.g. heating boilers), oil refineries, internal-combustion engines, etc.

Despite the simplicity of the chemical reaction of forming calcium carbonate on the surfaces of the water flow elements, the cohesion of the precipitated parties on the flow surfaces, which in reality describe the strength of the chemical bonds between the atoms of the precipitated particles and the flow surfaces, depends on crystal form, particle size distribution of the agglomerations, electro-kinetics potentials, etc. Therefore, the initial stage of nucleation greatly affects the maintenance, the performance and the financial aspects of large industrial plants.

By applying quantum electrodynamics calculations for both the nucleating matter and the electromagnetic field in the presence of a third body (surface), simple physical solutions can be introduced in order to avoid scaling, substituting thus the chemical methods used extensively today.

TEM images of crystals formed in the presence of the magnetic field obtained in Jozef Stefan Institute, Department for Nanostructured Materials. (a), compared to the crystals obtained without the applied magnetic filed (b); the three crystallization forms can be observed: A- aragonite, C-calcite, V-vaterite. S. Kobe et al. / Materials Science and Engineering C 23 (2003) 811-815 814